dysphemism vs understatement

dysphemism

noun
  • The use of a word or phrase carrying negative connotations or imagery (especially one that is derogatory, offensive or vulgar) to replace a (more) neutral original. 

  • A word or phrase that is used to replace another in this way. 

understatement

noun
  • A figure of speech whereby something is made to seem smaller or less important than it actually is, either through phrasing or lack of emphasis, often for ironic effect. 

  • An incomplete disclosure that intentionally withholds relevant information. 

  • An instance of such phrasing or lack of emphasis. 

How often have the words dysphemism and understatement occurred in a corpus of books? (source: Google Ngram Viewer )